1. Field of the Invention
The invention relates to a power-driven screwing head having means for disengaging the drive when a predetermined depth of screw penetration has been attained.
2. Description of the Prior Art
Screwing heads for screwing together wooden, chipboard and plasterboard panels have been proposed incorporating a coupling which is in the form of a slipping coupling, which does not or does only to an unsatisfactory degree permit screws to be screwed-in to a specific depth of penetration.
German Utility Model No. 7 624 784 discloses a screwdriver having an annular abutment face by which the screwing-in process is terminated when the screwheads have reached the desired depth of penetration into plasterboard panels. Regardless of whether it has a fixed or rotatable stop, damage to the screwheads when using a motor drive is inevitable with this screwdriver, since there is no coupling or clutch disengagement. Damage to screwheads must be avoided in interior construction work, since otherwise rust spots occur which are unsightly.
Devices of this type have also been proposed with releasable couplings and which, when the desired depth of penetration of the screw is attained, are automatically changed to the disengaged position. These devices are of complicated construction and are therefore also expensive, so that their use becomes practicable only for larger companies, but not for smaller installers or for the home handyman.
Accordingly, it is an object of the invention to provide a power-driven screwing head which is of simple design which is inexpensive to purchase and which is thus suitable for small industrial installers and for name applications, and which, while avoiding damage to screwheads and to the material into which the screws are to be screwed, reliably operates only to the depth to which it is desired that the screws penetrate.